Stonewall is usually the holy grail when it comes to jungling but I have to disagree with him here.
Ranking Mundo and Taric above Xin Zhao and Hecarim is just absurd, "Win Nao" has been and still is one of the most popular and strongest junglers in both solo queue and competitive play, easily up there with Volibear and VI. He has incredible dueling power, his ganks are great, he scales well into late game, he can build quite tanky and deal damage, his sustain is decent, his cc is above average..
What does Mundo bring? a skill shot slow and his ability to very often run from a lost fight. He gets counter jungled so hard because he runs so low on hp.
Taric? he's a flavour of the month because he's vastly overpowered at the moment, if you see a Taric as the enemy jungle you counter jungle instantly, he cant 1v1 a bruiser, sure he has great sustain, he's an amazing tank but if you actually ward he has 0 ganking power.
Hecarim, sure he CAN BE shut down very early but a good Hecarim will avoid this and good God, if this champion starts getting a few kills/assists, there's snowballing and there's Heca-balling. Again, great sustain, very good damage, quite tanky, amazing initiation, above average cc.
Also, as for J4 overshadowing Xin, I think that is hilarious, while I agree J4 is a strong pick right now, he is far stronger in top lane or as double bruiser bot. A good Xin will take advantage of J4's awful mana pool, no sustain and mediocre 1v1 in the jungle and make your life hell.